Organic photoconductor with carboxy group containing fluorene or fluorore

ABSTRACT

Photosensitive material for electrophotography containing as a sensitizer the compounds of the formula:   WHEREIN R1, R2 and R3 are selected from the group consisting of nitro, cyano, halogen, trifluoro-methyl, acyl, lower alkyl, lower alkoxy, aryl, aralkyl, and hydrogen; X is selected from the group consisting of oxygen and malononitrile; R4 is selected from the group consisting of, substituted or non-substituted, alkyloxy, alkylamino, aralkyloxy, aralkylamino, aryloxy, and arylamino; and R1, R2, R3 may be the same or different.

United States Patent 11 Nishide et al.

n] 3,864,126 1 1 Feb.4,l975

1 ORGANIC PHOTOCONDUCTOR WITII CARBOXY GROUP CONTAINING FLUORENE 0R FLUORORE [75] Inventors: Katsuhiko Nishide, Yokohama;

Tsuyoshi Eida, Chiba, both of Japan [73] Assignee: CanonKabushikiKaisha.Tokyo,

Japan [22] Filed: Jan. 8, 1974 [21] App1.No.:431,730

[30] Foreign Application Priority Data Jan. 10, 1973 Japan 48-5774 [52] US. Cl 96/l.5, 96/16, 252/501 [51] Int. Cl G03g 5/06 [58] Field of Search 96/15, 1.6; 252/501 [56] References Cited UNITED STATES PATENTS 3,287,114 11/1966 Hoegl 96/15 3,408,190 10/1968 Mammind 96/15 3,556,785 1/1971 Baltazzi 96/15 3,752,668 8/1973 Baltazzi 96/15 Primary ExaminerRoland E. Martin. Jr. Attorney, Agent, or Firm-Fitzpatrick, Celia. Harper & Scinto [57] ABSTRACT Photosensitive material for electrophotography con taining as a sensitizer the compounds of the formula:

R con 3 Claims, No Drawings ORGANIC PHOTOCONDUCTOR WITH CARBOXY GROUP CONTAINING FLUORENE OR FLUORORE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to photosensitive materials for electrophotography. More particularly, it relates to the addition of electron acceptive compounds for sensitizing an organic photoconductive material.

2. Description of the Prior Art It is known that a number of organic compounds are used in preparing a photoconductive member for electrophotography, While these organic compounds have several advantages as compared with inorganic photoconductive compounds, they have yet some drawbacks to be removed. A serious'drawback is that they are of extremely low sensitivity and in most cases their maximum absorption of spectra are without the range of ultraviolet rays and thus they cannot be conveniently employed in practical uses.

It is also known that the above drawback may be avoided by adding to the organic photoconductive member electro acceptive compounds which are called rr acid or Lewis acid. For example, as described in Japanese Pat. Publication No. 16587/1967, the addition of less than lmol% of an electron acceptive compound to an organic photoconductive material provides particularly high photosensitivity for the range of ultraviolet rays. In U.S. Pat. No. 3,484,237, a large amountof electron acceptive compound is added, i.e. 49 to 123 mol% of trinitro fluorenone as the electron acceptive compound is added to poly-9-vinylcarbazole of organic photoconductive material to provide high sensitivity for white light.

However, since the electron acceptor compounds as used in such sensitizing methods have strong polar groups, they are generally insoluble in organic solvents or easily crystallized. Thus, the kinds of solvents which can be used, are disadvantageously limited and it is therefore difficult to select arbitarily in preparing a photosensitive layer a suitable solvent for the preparation conditions thereof. In addition, since the electron acceptor compounds crystallize markedly easily when their solvents vaporize at coating step, it is difficult to form an even photosensitive layer. Furthermore, since the electron acceptor compounds are slightly soluble, the amount of the electron acceptor compound to be added, is limited and it often follows that the sensitizing effect of the electron acceptor compound cannot be completely attained in practical usages. Furthermore, since the comparativity of the electron acceptor compound with the organic photoconductive material is low, the electron acceptor compound crystallizes on the surface of photosensitive layer after a relatively short storage period, and now they cannot be used.

SUMMARY OF THE INVENTION An object of this invention is to provide novel electron acceptor compounds which can be used as a sensitizer in com hination with organic photoconductive matcrials.

Another object of this invention is to improve the solubility of electron acceptor compounds in organic solvents so as to increase the amount of the electron acceptor compound to be added and the kinds of solvents to be used.

Further object of this invention is to increase the DESCRIPTION OF THE PREFERRED EMBODIMENT The above objects can be achieved by using electron acceptor compounds of the formula:

R l COR 2 X i i wherein R R and R are nitro, cyano, halogen, trifluoromethyl, acyl, lower alkyl, lower alkoxy, aryl, aralkyl, or hydrogen; X is oxygen or malononitrile group connected by double bond; R is substituted or nonsubstituted, alkyloxy, alkylamino, aralkyloxy; aralkylamino, aryloxy or arylamino group containing 4 to 30 carbon atoms; and R R and R may be the same or different and furthermore the carbon number of the lower alkyl or lower alkoxy group is preferably 1 to 6 from the standpoint of easy production.

The additional advantage which is brought about by using the above compounds, is that there may be reduced or completely removed plasticizers which are added in the preparation of photosensitive layer and which are apt to reduce the sensitivity of the photosensitive layer.

The representatives are used herein may be given below.

1. 7-nitro-9-fluorenone-l-carboxylic acid butyl ester 2. 4-nitro-9-fluorenone-l-carboxylic acid octyl amide 3. 2,7-dinitro9-fluorenone-l-carboxylic acid-3- methyl-4-isopropylphenyl ester 4. 3 nitro-6-bromo-9-fluorenone-lcarboxylic P-isopropylbenzyl ester 5. 2-nitro-6,7-dichloro-9-fluorenone-l-carboxylic acid dihexyl amide 6. 2,7-dichloro-9-fluorenone-l-carboxylic acid benzyl amide 7. 2,6,7-tribromo-9-fluoreneone-l-carboxylic acid lauryl amide 8. 7-cyano9-fluorenone-l-carboxylic chlorobutyl ester 9. 7-nitro-9-fluoreneone-2-carboxylic acid cetyl amide l0. 4,5,7-trinitro-9-fluorenone-Z-carboxylic acid octyl ester 1 l. 2,7-dichloro-9-fluorenone-3-carboxylic acid P- anisidino l2. 2-cyano -9-fluorenone-3-carboxylic acid P-acetophenyl ester acid acid 4- l3. 2,7-dinitro-9-fluroenone-4-carboxylic acid hexyl 4 l4. 2,5,7-trinitro-9-fluorenone-4-carboxylic acid lauryl acid '3 l9. 4,5-dinitro-7-acety1-9-fluorenone-2-carboxylic acid P-chlorobenzyl ester 20. 4,5,7-trinitro-9-fluorenone-2-carboxylic acid decyl amide 21. 7-chloro-8-methyl-9 fluorenone-2-carboxylic acid hexyl amide 22. 4,5-dichloro-7-methoxy-9-fluorenone-Z-carboxylic 27. 1,6-dichloro-9-dicyanomethylene fluorene-4- carboxylic acid myristyl ester 28. 6,7-dibrorno-9-dicyanomethylene fluorene-lcarboxylic acid 3,4-xylidide 29. 2,5,7-trinitro-9-dicyanomethylene fluorene-4- carboxylic acid stearyl amide 30. 4,5 ,7-trinitro-9-dicyanomethylene fluorene-2- carboxylic acid oleyl ester The above compounds may be generally prepared from the corresponding 9-fluorenone carboxylic acids and 9-fluorenone carboxylic acid ester or amide derivatives may be prepared according to conventional methods of preparing ester or amide. 9-dicyanomethylene fluorenone carboxylic acid ester and amide derivatives may be prepared by reacting the corresponding 9- fluorenone carboxylic acid with malononitrile and thereafter esterifying or forming amido, or by reacting 9-fluorenone carboxylic acid esteror amido derivatives with malononitrilef The typical methods of preparing the above compounds are givenbelow. Preparation Example 1 2,7-dinitro-9-fluorenone 4 -carboxylic acid hexyl ester [(13) of the above mentioned compounds] 3.14g (0.01 mol) of 2,7 dinitro 9 fluorenone -4 carboxylic acid was dissolved in 50 ml of hexyl alcohol by heating and, after adding three drops of sulfuric acid, was kept at 150C for 4 hours. After cooling, the precipitated yellow crystal was filtered and the filtrate was distilled to dryness under reduced pressure. The residue was recrystallized with the above crystal from n hexane and thus there was obtained 2,86g of the end product. Elemental analysis:

Elemental analysis:

Calc. Found C 60.29% 60.40% H 4.56% 4.51% 6.98%

. Elemental analysis:

' Calc. Found C 61 .87% 61.52% H 4.07% 3.99% O 12.55% 12.48%

Elemental analysis:

Calc. Found C 56.04% 56.17% H 4.50% 4.46% O 8.91% 8.86%

Preparation Example 4 4,5,7 trinitro 9 fluorenone 2 carboxylic decyl amide (20) I 378g (0.01 mol) 0f 4,5,7-trinitro-9-flurorenone-2- carboxylic acid chloride as prepared in preparation Example 3 was heated with 50 ml of decylamine at C for 3 hours and decylamine was distilled under reduced pressure. The residue was recrystallized from hexane and there was obtained 4.06g of a light yellow end product, Elemental analysis:

Elemental analysis:

Cale. Found C 57.82% 57.71% H 5.27% 5.32% O 11.24% 11.20%

Preparation Example 5 l,6-dichloro-9-dicyano-methylene carboxylic myristil ester (27) 2.93g (0.01 mol) of 1,6-dichloro-9-fluorenone-4- carboxylic acid was refluxed in 300 ml of methyl alchohol and after adding 2.0g (0.03 mol) of malononitrile and 2 drops of piperidine, was refluxed for additional 20 hours. After cooling, the precipitated crystal was filtered and there was then obtained 2.3 lg of 1,6- dichloro-9-dicyanomethylene fluorenone 4-carboxylic acid it refluxed in 30 ml of thionyl chloride for 5 hours to form the corresponding acid chloride.

After distilling excess thionyl chloride, it was refluxed in 40 ml of myristyl alcohol at 80C for 3 hours and after distilling myristyl alcohol under reduced pressure, it was recrystallized from N-hexane and there was then obtained 3.18g of the end product. Elemental analysis:

fluorenone-4- Organic photoconductive materials as herein used are preferably such as to act as the electron donative member as the above compounds when combined with organic photoconductive materials can act as the electron acceptor member. Thus they include low molucular type organic photoconductive materials such as amyl hydrazone derivatives, oxadiazole derivatives, pyrazoline derivatives, imidazolone derivatives, imidazolinethione derivatives, benzimidazole derivatives, benzoxazole derivatives, and benthiazole deriva tives; polymer containing heterocylic ring such as carbazole ring or polynulclear aromatic rings such as naphthalene ring or anthrathene ring which are disclosed for example in Japanese Pat. Publication Nos. 10966/1959, 812/1961, 18674/1967. 25230/1967 and the like.

Representative materials used as an organic photoconductive material in the present invention are as follows:

A. Polymer having a carbazole ring such as poly-9- vinylcarbazole, 9-vinylcarbazole copolymer, 3-nitro-9-vinylcarbazole copolymer, 3- methylamino-9-vinylcarbazole copolymer, nitrated poly-9-vinylcarbazole, 3,6-dibromo-9- vinylcarbazole copolymer, poly-9-vinyl-3- aminocarbazole, chlorinated poly-9- vinylcarbazole, thiocyanated poly-9- vinylcarbazole, cyanated poly-9-vinylcarbazole, brominated poly-9-vinylcarbazole, 3-iodo-9- vinylcarbazole copolymer, poly-3,6-diiodo-9- vinylcarbazole, poly-3-benzylideneamino-9- vinylcarbazole, 3,6-dibromo-9-vinylcarbazolc copolymer, aw-bis-carbazole-alkane derivative, vinyl anthracene 9-vinylcarbazole copolymer, (2 or 3)-vinyl-9alkyl-carbazole polymer or eopolymer (the alkyl group is selected from the group consisting ofprimary alkyls such as methyl, ethyl and pro- Py B. Aromatic amino derivatives such as aminopolyphenyl, (allylidene) azines, N-N'-dialkyl-N, N-dibenzylphenylenediamine, N,N,N',N-tetrabenzyl-phenylenediamine, N,N-diphenyl-P- Phenylenediamine, N,N-dinaphtyl-pphenylenediamine, 4,4-dimethylaminophendiphenone.

C. Diphenylmethanes and triphenylmethanes such as diphenylmethane dye dye leuco base and triphenylmethane dye leuco base.

D. Heterocyclic compounds such as oxadiazole, 5- aminothiazole, 4,1,2-triazole, imidazolone, oxazole, imidazole, pyrazoline, imidazoline, polyphenylenethiazole, 1,6-methoxyphenezine, pyrazolinopyrazoline derivatives and the like.

Compounds having a condensed ring such as benzothiazole, benzimidazole, and benzoxazole, for example, -tetraphenylhexatriene, 2-(4- diaminophenyl-benzoxazole and 2-(4- dimethylaminophenyl) benzoxazole, aminoacridine, quinoxaline, diphenylenehydrazones, pyrrocoline derivatives, 9,10-dihydroanthraoene derivatives and the like.

F. Compounds having a'double bond such as acylhydrazone, ethylene derivatives, l,l.6,6-tetraphenylhextraiene. and the like.

G. Condensation products such as condensation products of aldehydes and aromatic amines. reaction product of secondary aromatic amines and aromatic halides. polypyromethane-imidopoly-pphenylene-l ,3,4-oxadiazole and the like.

H. Vinyl polymers (except polyvinylcarbazole) such as a-alkylacrylic acid, amide polymers polyvinylacridine, poly-[ l ,5-diphenyl-3-(4-vinylphenyl)-2- pyrazoline], poly-(1,5-diphenylpyrazoline), polyacenaphthylene, neuclear substituted polyacenaphthylene, polyvinylanthracene, poly-2-vinyldibenzothiophene and the like.

Materials providing good results of sensitizing treatment of this invention among these organic photocon ductive materials are polymers having a carbazole ring and their derivatives, aromatic amino derivatives. diphenylmethane derivatives and triphenylmethane derivatives.

1n practising this invention, the organic photoconductive materials and the compounds of this invention are dissolved in proper solvents. The compounds of this invention may be dissolved in numerous kinds of solvents and thus the most proper solvent may be selected from numerous solvents depending upon an organic photoconductive material to be used. The amount of the compound of this invention varies depending upon the purpose thereof. For example, where it is coated on a substrate such as paper, film, and the like and used as an almost colorless or almost colorless, transparent photosensitive layer, it is added within the ratio of0.01 to 10 mol, preferably 0.1 to 5 mol per mol of organic photoconductive material (if the photoconductive material is a polymer, it is calculated based upon the molecular weight of unit monomer of the polymer). In this case, high photosensitivity for ultraviolet range is provided. If high sensitivity for visible light is also required, it may be achieved by adding dye sensitizers in such an amount not to color strongly thephotosensitive layer.

If high sensitivity for white light color is needed as in a master photosensitive plate and if coloration of the photosensitive plate is negligible, high ratio of 10 to mol per 100 mol of organic photoconductive mate rial may be used to provide high sensitivity for visible light. The solution containing the photoconductive material and the compounds of this invention may if necessary include binder resins and other additives, which are coated on a substrate or some special cases used in the form of self-substrate.

The following examples illustrate the embodiments of this invention, but do not limit the scope of the invention. Comparison Example 1 To the solutions prepared by dissolving 2.0g of poly9- vinylcarbazole in 30ml of the following solvents were added 2,4,7-trinitro fluorenone (TNF) of 10 mol% and 100 mol% based of poly-9-vinylcarbazole. The solubility of TNF in the solvents were measured and indicated in Table below. wherein reference symbol 0 means that TNF is soluble and X means that TNF is insoluble.

100 mol of the compounds as listed above TNF Solvent mol 7! 100 mol Chlorobenzene Tetrahydrofuran Cyclohexane Pyridine Dimethylform amide (DM F) Dioxane l,2 'dichl0roethane Methylene- Chloride Chloroform Toluene Benzene Carbon disulfide O OO OOOO .taining 3.26g of 2,4,7-trinitrofluorenone, it was observed that 2,4,7- trinitrofluorenone was crystallized and predipitated immediately after the formation of photosensitive layer. Precipitation due to crystallization is judged from opaqueness of the photosensitive layer and unevenness of the surface'thereof. In this comparison example, where the above compounds (1) to (30) were used in place of 2,4,7-trinitrofluorenone, no precipitation due to crystallization was observed. In addition, pyridine was used in place of dimethyl formamide with similar results. Comparison Example 3 Three photosensitive layers comprising polyvinylcarbazole; polyvinylcarbazole, and 2,4,7- trinitrofluorenone, and polyvinylcarbazole, 4,5,7- trinitro-9-fluorenone-2-carboxylic acid octyl ester, respectively, were prepared on 75p thick polyester film whose surface was made hydrophilic, by coating. The thickness of the resulting photosensitive layer was adjusted to 4p. thickness. By winding the polyester film around the rods having the following diameters with the surface thereof outward, cracking of the photosensitive layer was tested. In Table below, reference symbol X means that the cracking of photosensitive layer occurs and 0 means that no cracking occurs.

m-phenylenediamine, 2g of polystyrene, 144mg of2,5,-'

7-trinitro-9-dicyanomethylene fluorenone-4-carboxylic acid stearyl amide (compound (29) and 40ml of toluene was coated on a paper which was treated not to permeate solvent, and dried to provide a photosensitive paper. The thickness of the photosensitive layer was about 7,u..

The photosensitive layer was charged, exposed to light, and developed as in Example 1 and there was thus obtained an excellent image. The proper exposure amount was 550 Lux sec.

EXAMPLE 3 A solution prepared by dissolving 2g of poly-3- methyl-9-vinylcarbazole and 38mg of 2,7,-dinitro-9- fluoroenone-4-carboxylic acid hexyl ester compound (13) in 35ml of chlorobenzene and a solution prepared by dissolving 11.6mg. of 9,9-diethyl-3,3- dicarbazolyl phenylmethyliodide (sensitizing dye) in 5ml of methylene chloride were mixed to prepare a photosensitive solution. The photosensitive solution was coated on a transparent polyester film on which aluminum was thinly deposited, and dried to form a transparent photosensitive film having a 6p. thick photosensitive layer. The photosensitive layer so prepared was charged, exposed to light and developed as in Example 1 and there was then obtained an excellent copied image. The proper exposure amount was 150 Lux sec.

EXAMPLE 4 A solution composed of 2g of poly-9-vinylcarbazole, 4.9g of 4,5,7-trinitro-9 fluorenone-2-carboxylic acid octyl ester compound (10) and 30ml of chlorobenzene was coated on an aluminum plate to form a 10p. thick dry layer. The photosensitive plate so prepared was applied to a rotation type electrometer and after charging negatively at -6KV, exposed to a tungusten lamp (effective illumination intensity, 14.4 Lux Ex- Diameter PVK TNF 4,5,7-trinitro- (mm) (not added) 9-fluorenone-2- carboxylic acid octyl ester 10 mol% 100 mol% 10 mol% 100 mol% 6 O O O O O 5 0 o X o 0 4 X X X 0 0 3 X X X X 0 EXAMPLE 1 posure amount required for decaying the initial poten- A solution composed of 2g of l,3,5- tial 950V to thereof (half-decay exposure) was 4.4

triphenylpyrazoline, 2g of polyvinyl butyral resin, 70.4mg. of 7-cyano-9-fluroenone-l-carboxylic acid 4- chlorobutyl ester [compound (8)] and 50 ml ofethanol Lux sec.

In this example, where polyl-3-chloro-9-vinylcarbazole was used in place of poly-9-vinylcarbazole,

half-decay exposure was 4.0 Lux sec. and where poly- 3,6-chloro-9 -vinylcarbazole was used, the half-decay exposure was 3.6 Lux sec.

EXAMPLES to in Example 4 with Electrometer with the results as 10 shown below.

ratio of said compound to said organic photoconductive material being 001 120 mols to 100 mols.

2. Photosensitive material for electrophotography according to claim 1 in which the compound represented by the formula of claim 1 is added in a ratio of 0.01 to 10 mol per 100 mol of the organicphotoconductive material.

3. Photosensitive plate for electrophotography comprising one or more organic photoconductive materials Example added Amount (mol% based Initial Half-decay compound on poly-9-vinyl potential exposure carbazole) 5 com- 1 4.04g (120 mol%) 920V 5.2 Lux sec.

pound 6 do. 5 5.40;; (100 do.) 950V 5.0 do.

7 do. 3.7lg (80 do.) 880V 6.0 do.

8 do. l7 2.39g (50 do.) 900V 11.0 do.

9 do. 1.39g do.) 960V |8.5 do.

10 do. 30 1.36g (20 do.) 960V 240 do.

We claim: and one or more compounds of for sensitizing said phol. Photosensitive material for electrophotography comprising one or more organic photoconductive materials and one or more compounds of the formula:

4 coR wherein R R and R are, the same or different, nitro, cyano, halogen, trifluoromethyl, acyl, lower alkyl, lower alkoxy, aryl, aralkyl, or hydrogen; X is oxygen or malononitrile; and R is, substituted or non-substituted, alkyloxy, alkylamino, aralkyloxy, aralkylamino, aryloxy, or arylamino, containing 4 to 30 carbon atoms, the

toconductive materials of the formula:

' R CORli wherein R R and R are, the same or different, nitro, cyano, halogen, trifluoromethyl, acyl, lower alkyl,

material being 10 to 120 mols to mols.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,864,126 Dated February 4, 1975 Inventor(s) KATSUHIKO NISHIDE ET I AL It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 8, "stearly" should read -stearyl-;

Column 3, line 49, "2,869" should read -2.86g--;

Column 4', line 34, "Or" should read --of-;

Column 5, line 14, "molucular" should read mol ecular-;

Column 5, line 22, ".polynulclear" should read --polynuclear-T Column 5, line 54, "4,4" should read --4',4'-;

Column 5, line 57, delete "dye" (second occurrence) Column 5, line 65, delete "tetraphenylhekatriene";

Column 5, line 66, 4'diaminophenylf' should read (4'diaminophe nyl Columnl6, line 16, fneuclear" shouldread -nuclear;

Column 7, line20, "trinitrofuruorenone" should read trinitrofluorenone;

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,864,l26 Dated Februarv 4 1975 fls) KATSUHIKO NISHIDE ET AL. PAGE 2 It is certified that error appears in the above-identified patent and that said Letters Patent are, hereby corrected as shown below:

Column 7, line 23, "photossnsitive" should read photosensitive;

Column 7, line 31, "predipitated" should read precipitated;

Column 8, line 8, "tungusten" should read -tungsten-; I

Column 8, line 50, "tung u-sten" should read tungsten;

Claim 1, column 9, line 26, after 'compounds" add -for sensitizing said photoconductive materials-;

Claim 3, colu'nm 10, line 36, "aralkykoxy" should read aralkyloxyi v I Signed and sealed this 10th day of June 1975.

(SEAL) Attest:

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks 

2. Photosensitive material for electrophotography according to claim 1 in which the compound represented by the formula of claim 1 is added in a ratio of 0.01 to 10 mol per 100 mol of the organic photoconductive material.
 3. Photosensitive plate for electrophotography comprising one or more organic photoconductive materials and one or more compounds of for sensitizing said photoconductive materials of the formula: 